(i) Technical Field
A certain aspect of the embodiments discussed herein is related to a Doherty amplifier and a semiconductor device. Another aspect of the embodiments is related to a Doherty amplifier and a semiconductor device including FETs.
(ii) Related Art
A Doherty amplifier is used as radio communications amplifier (see Japanese Patent Application Publication No. 2005-322993). The Doherty amplifier includes a carrier amplifier and a peaking amplifier. The carrier amplifier is an amplifier that primarily amplifies an input signal. The peaking amplifier is an amplifier that amplifies the peak of the input signal. For example, the carrier amplifier always amplifies the input signal. In contrast, the peaking amplifier amplifies the input signal only when the input signal has power equal to or higher than a predetermined level.
The Doherty amplifier has a difficulty in downsizing because of the use of both the carrier amplifier and the peaking amplifier.